The geology and ore controls in and around the McIntyre mine at Timmins, Ontario, Canada.

摘要

This thesis describes the relationship of hydrothermal alteration and copper and gold mineralization to the sequence of volcanic, intrusive and deformational events in and around the McIntyre mine (ie. the Hollinger-McIntyre-Coniaurum complex) at Timmins, Ontario.;The development of albitized plagioclase phenocrysts in various porphyry intrusions during late magmatic/early hydrothermal alibtization was followed by microstockwork sericite (proximal)/chlorite (distal) alteration and disseminated carbonate alteration, defining an extensive alteration halo to the mineralized complex. Copper and gold mineralization has been linked to a second phase of albitization, developed as an aggressive, non-selective replacement of porphyry and volcanics to rock resembling albitite, in localized hydrothermal centers (i.e. the copper ore zone in the Pearl Lake porphyry on McIntyre, and the central ore (gold) zone developed along the western contact of the stock, and its strike and down-dip extensions eastward along the north and south porphyry contacts). This albitization is probably related to the emplacement of a series of albitite dikes which intruded porphyry and volcanics but are locally veined. The configuration of the copper ore zone is largely defined by the distribution of hematite alteration, developed as an annular zone of pervasive pink-red coloration of albitized porphyry. Hematite alteration was followed by a second more intense, but more localized sericite event, phyllic alteration, developed as khaki-green, fracture-controlled sericite ;The complex is interpreted as having developed as a gold-dominated porphyry-type system with porphyry copper stockwork mineralization surrounded by auriferous quartz veins and stockworks. Mineralized structures were developed as a result of delamination and fracturing of the layered volcanic sequence during porphyry intrusion, followed by repeated episodes of hydrothermal fracturing, so that emplacement and crystallization phenomena related to both the porphyry and the albitites created an environment for mineralization.;Post-mineralization, penetrative deformation, typically involves cleavage and linear fabric development with corresponding modification of all pre-existing geometries, so that the configurations of the Central Tisdale anticline, the Pearl Lake porphyry and the orebodies, all reflect strain related to this deformation. The Hollinger fault system reflects late (post-diabase dike) brittle failure along a zone of high strain, developed in the central ore zone at the Hollinger mine.;The mineralized complex is centered on the Pearl Lake porphyry, which intruded a homoclinal sequence of Archean magnesian and iron tholeiitic basalts of the Tisdale Group, along the south limb of the Central Tisdale anticline. Superposition of textural styles and associated mineral assemblages records the evolution of the mineralized complex from early, barren hydrothermal events related to porphyry intrusion, to post- and/or syn-albitite hydrothermal events more closely related to copper and gold mineralization, and finally to the modification of the hydrothermally altered and mineralized system by penetrative deformation. This evolution is linked by a repetition of albite-dominated activity and marked by a transition from early, widespread, pervasive and microstockwork-controlled hydrothermal activity to more localized, (macro)fracture-controlled hydrothermal events confined to major hydrothermal centers.